Development of a Method to Model Flexible Hose in FE Linear Dynamics Simulations

Linear dynamics simulations are performed on engine components to ensure structural integrity under dynamic loading. The FE model of the engine assembly must be prepared accurately to avoid under or over design of the engine components. Flexible hoses are present at pipe routings and modeling them in simulations is a challenge because the stiffness of the composite is not known. Current method includes using linear mass and spring elements instead of the hose with assumed stiffness, which leads to lack of confidence in the FE model. The hose under study in this paper is a rubber composite with a knitted reinforcement layer. This work involves a multiscale modelling approach using Representative Volume Element (RVE) for homogenization of yarn and rubber material properties to model composite hose in FEA. A RVE geometry is created which is a unit cell representation of the composite consisting of the knitted yarn and surrounding rubber. Orthotropic elastic properties are established at microscale by performing FE homogenization on the RVE geometry using ANSYS material designer module. The homogenized density of the RVE when applied to the macroscale hose geometry, computes the mass of the hose close to the measured value. Modal analysis simulation for the hose is conducted in free-free and fixed-fixed conditions, where the hose is defined using the established properties. Experimental modal analysis is performed on the hose with the same boundary conditions. Natural frequencies and mode shapes obtained from simulation and experiments show good agreement. A predominantly automated approach to characterize the stiffness of the hose is presented and it is suggested that the hose shall be modelled using orthotropic elastic properties in linear dynamics simulations for a more accurate FE model. Keywords: Reinforced knitted rubber hose, FEA, RVE, Experimental modal analysis